Johnstown is the largest city in Cambria County, Pennsylvania, United States. The population was 18,411 as of the 2020 census. Located 57 miles (92 km) east of Pittsburgh, it is the principal city of the Johnstown metropolitan area, which is located in Cambria County and had 133,472 residents in 2020. It is also part of the Johnstown–Somerset combined statistical area, which includes both Cambria and Somerset Counties.